After a very rigorous evaluation program,
the RAAF earlier this year selected the Lockheed Martin/Rafael AGM-142
Raptor as the new Stand Off Weapon (SOW) for the F-111. The decision
came as a surprise to most observers, as it was generally expected that
the slightly cheaper Rockwell AGM-130 rocket boosted glidebomb kit
would
have been the preferred choice. The RAAF however had good reasons for
choosing the way they did, as will shortly be illustrated.

The AGM-142 will typically be
carried in pairs by the F/RF-111C AUP. The missile is functionally
split
into a guidance and navigation section in the nose, the warhead section
(denoted by red stripes), the rocket motor section, and the hydraulics
and control section in the tail of the airframe. The blast
/fragmentation warhead forms a load bearing fuselage section, whereas
the penetration warhead is a sub-calibre munition mounted in a
structural fuselage section built solely for this purpose. The conduits
along the warhead section carry electrical cables between the guidance
and navigation section and the aft hydraulics section.

Warheads may be interchanged. Late models of the AGM-142 now have
provisions for adding a GPS receiver to the IMU, which would provide
for
high midcourse navigational accuracy in any extended range versions
(using turbojet or longer burn rocket motors). Recent reports indicate
that the RAAF now intend to use the AGM-142 also for anti-shipping
strike. Compared to the established radar guided AGM-84 Harpoon, the
AGM-142 has twice the warhead weight and thus killing power, as well
the
operator may select the most vulnerable aimpoint on the target vessel
to maximise inflicted damage. The AGM-142 has similar range to the
Harpoon when launched at altitude, but is supersonic and provides no
warning of its approach to listening ESM as it uses a passive optical
seeker (Artwork Carlo Kopp).

The SOW
program grew out of a lengthy internal debate within the RAAF, which
began in the late eighties. At that time it was becoming increasingly
apparent that the regional air defence environment was becoming
significantly more capable than in previous decades. Of some concern
was
the regional proliferation of the capable Soviet designed SA-10A/B/C/D
(Almaz S-300P/PM/PMU/PMU-1/5V55/48N6) area defence SAM, late models of
which had the potential to threaten the F-111 when attacking targets at
low level using datalink or laser guided bombs.

The SA-10's
Flap Lid phased array engagement radar supported by the Clam Shell FMCW
low level acquisition radar are both reputedly quite resistant to
jamming (see AA Sept 95), and it was readily apparent that the RAAF's
existing inventory of weapons could expose the aircraft to potentially
dangerous tactical situations when penetrating defended airspace.
Clearly a new weapon was required to deal with such air defence
environments, the alternative was the potentially prohibitive cost of
losing aircrew and aircraft in any major regional or extra-regional
confrontation.

A
capability submission for a stand off weapon was then prepared during
the early nineties by HQ ADF and subsequently endorsed. Once
endorsement
occurred, the RAAF defined an Equipment Acquisition Strategy (EAS)
document which set out the process for selecting and acquiring a
suitable weapon. While early thought favoured the AGM-130 weapon,
further examination of alternatives indicated that the Rafael Popeye
and its USAF AGM-142 derivative would be viable candidates and these
two very closely related weapons were included in the shortlist. As the
requirement was tightly defined in a number of key areas and only these
types qualified, the RAAF dispensed with the customary ITR and
tendering process and directly evaluated the two types.

The stated
objective of the program is to improve the survivability of the F-111
when conducting strategic strike operations. Earlier DSTO studies
indicated that this was best achieved by using a standoff weapon, and
this conclusion drove the ADF's selection process. The evaluation
criteria were therefore focussed on the selection of the weapon which
would best reduce susceptibility to attack, while meeting defined
mission objectives.

The RAAF
evaluated three alternatives, these were the US FMS supplied Rockwell
AGM-130 and Lockheed Martin/Rafael AGM-142, and the commercially bid
Rafael Popeye as used by the Israeli air force. The evaluation was
split
into four components.

The first
of these was the evaluation of the vendor's formal proposals for the
supply of the weapon, and essentially involved analysing the paper
proposals against the RAAF's stated technical and operational
requirements.

The second
component of the evaluation was a funded study of integration issues in
relation to the F-111C AUP digital weapon system. This study, carried
out for both weapons, identified the effort required in software and
hardware modifications and integration testing to support the new
weapon
in the new digital avionic system.

The third
component of the evaluation was a stores carriage compatibility report
prepared by ARDU, which evaluated the required effort to certify the
carriage, employment and jettison of either of the weapons on the F-111.

The fourth
phase of the evaluation was carried out by DSTO, who had earlier
determined that a generic powered stand off weapon was a better
proposition than an unpowered bomb or glidebomb. The second part of
DSTO's evaluation was thus split into a number of areas.

Both
missile seekers were evaluated for resolution performance and
sensitivity, and it was intended that both seekers also be flight
tested
to confirm the theoretical analyses. Only the AGM-142/Popeye thermal
imaging seeker was flight tested, as the RAAF were unable to acquire an
AGM-130 seeker in the required timescale.

Concurrently, DSTO conducted a survivability and lethality assessment
of
both missiles. The survivability analysis was based on a wide range of
scenarios, and focussed both on aircraft survivability and missile
survivability. These scenarios were based on both existing threat air
defence capabilities and threat SAM and AAA capabilities projected out
to 2010.

The
lethality analysis focussed both on weapon accuracy and warhead
effectiveness, for a very broad range of representative targets,
specified by the Air Force. The intent was to determine the relative
cost effectiveness of either weapon type, as this would determine in
turn required war stocks.

As seeker
accuracy was similar for both weapons, this analysis devolved down to
assessing the lethality of the standard blast fragmentation warheads
used in the weapons. Fragmentation patterns for the warheads were
analysed against the intended target sets. The analysis concluded that
the 800 lb warhead of the AGM-142/Popeye provided acceptable damage
levels for virtually all intended targets, and the additional punch of
the 2,000 lb Mk.84 warhead used in the AGM-130 provided little
additional advantage. The RAAF intend to use the new weapon with both
blast frag warheads and penetration warheads, although the latter were
not evaluated in detail. It is worth noting that warhead weight alone
is
not a deciding factor with penetration weapons, indeed the speed and
angle of impact and mechanical resilience of the penetrator make a
greater contribution to the weapon's ability to punch through
reinforced
concrete than sheer mass does.

The
conclusion of this complex evaluation process was that the longer
ranging AGM-142/Popeye weapon provided significantly better aircraft
survivability than the AGM-130 weapon, while still capable of
inflicting
acceptable damage levels on the intended target types. The additional
lethality of the AGM-130 was not found to offset the greater risks
imposed on the launch aircraft due its shorter launch ranges at all
altitudes. As the principal intent of the project was to improve F-111
survivability, the ADF concluded that the AGM-142/Popeye was the more
cost effective weapon.

Software
integration with the F-111C AUP will commence in September, 1996 and is
intended to continue until the weapon achieves IOC. Ground testing is
scheduled for April 1998, with flight testing planned for Q3/Q4 1998.
One test launch is planned for at this time. The Phase 1A of the
program, intended to provide an Initial Training Capability (ITC), is
planned for completion February 1999. Subject to budget approvals, the
Phase 2 Initial Operational Capability is planned for July, 1999.

As an
interesting side note, the USAF B-52G launch of a AGM-142 missile at
the
Woomera range was not, as incorrectly reported at the time, related to
the evaluation. At that time the USAF intended to carry out a AGM-142
launch demonstration from a B-52 on an intercontinental sortie, to
promote the USAF's new "Global Reach, Global Power" doctrinal model.
The purpose of the demonstration was to show that the USAF could engage
a point target flying directly from the continental US in a single pass
standoff attack. The only two US allies which had suitable test ranges
capable of supporting the release of a highly classified precision
weapon were Israel and Australia. Given the then volatile political
situation in the Middle East, Australia was approached and agreed to
host the demonstration, with all expenses paid for by the USAF. A
muddled DPR press release, which caused much upset in the SOW project
office, led to a flurry of enquiries from trade press and bidders
alike.
Alas it was purely unfortunate timing.The Lockheed Martin/Rafael
AGM-142 Raptor

The early
history of the Popeye is shrouded in the characteristic secrecy of
Israeli weapons development programs. Whilst rumours do abound that the
weapon is a derivative of the cancelled US Navy Condor missile,
reputedly sold off to the Israelis after the program was abandoned, AA
have been unable to confirm this.

The USAF's
AGM-142 Raptor is a derivative of the basic Israeli Popeye weapon, with
a moderate number of minor modifications intended to improve
compatibility with USAF platforms and the USAF's logistical system. The
weapon currently arms a fraction of the B-52 fleet and will be licence
manufactured in the US in a joint venture by Israel's Rafael and
Lockheed Martin.

The Rafael/Lockheed Martin
AGM-142
Raptor is the USAF version of the Israeli Popeye missile, and has a
range of minor modifications to suit the USAF operational environment.
The missile weighs 3,000 lb at launch, has a range in excess of 50 NM
when launched at altitude, and is extremely accurate with a thermal
imaging seeker which datalinks a picture to the F-111 navigator's
cockpit display. With an 800 lb blast frag warhead or penetrator, the
missile is particularly lethal against high value targets such as air
defence and command -control -communications sites.

During the
late eighties the USAF sought a standoff missile for their B-52, to
enable it to attack from outside the area defences of a target. The
Rafael Popeye was then being introduced into IDF service on the F-4E,
and the USAF in 1988 contracted Rafael and Boeing, the latter the
authors of the B-52 offensive avionic system, to integrate the weapon
with the B-52G and provide an initial supply of missiles, respectively.
To date all USAF AGM-142 stocks have been supplied by Rafael, but
future
stocks will be supplied by the joint venture company, with some
components manufactured in the US.

The missile
was initially designated the Have Nap by the USAF, later redesignated
the AGM-142, and recently renamed the AGM-142 Raptor. Unconfirmed
sources indicate the weapon was blooded during the Gulf Campaign, and
used to hit hard targets from outside Iraqi air defence coverage. The
political circumstances of the period meant that the US has to date
consistently denied the use of the weapon in the campaign, which would
no doubt aggravate many Middle Eastern former coalition members.

The AGM-142
is a rocket propelled air to surface standoff missile, with inertial
midcourse guidance and an electro-optical (TV or IIR) terminal seeker
which relays a picture to the launch aircraft via a datalink. The
weapon
operator will then update the weapon's aimpoint using a datalink
command channel from the launch aircraft, much like the GBU-15
(AGM-130)
and Walleye glidebombs. The datalink equipment is carried in a weapon
specific pod, as is the case with the GBU-15, AGM-130 and Walleye. The
missile weighs approximately 3,000 lb, is 190" in length, 21" in
diameter and has a wing span of 68".

The missile
can be refitted on the flightline with either a daylight TV seeker, or
a
8-12 micron band HgCdTe thermal imaging seeker, the latter only will be
used by the RAAF. The seeker has selectable wide and narrow field of
view modes, using an optical/mechanical selection mechanism. Wide FOV
would be used initially to acquire the target, and narrow FOV then
selected during the terminal phase of flight to allow the operator to
precisely choose the aimpoint (eg window or vent) he intends to put the
weapon through. The seeker is cooled by a closed cycle helium
refrigerator powered off the missile's internal 28V DC rail, earlier
USAF and Israeli models employed a open loop Nitrogen cooling system
fed
from a storage bottle.

Midcourse
navigation is performed with an inertial measurement unit, built around
three fibre-optic gyro (FOG) angular rate sensors and three mechanical
accelerometers. The guidance system is built around an Intel 486 based
processor module with up to 32 Megabyte of main memory, to provide for
long term growth capability in the missile's software. The choice of
the
486 CPU is unusual for an embedded weapons application, and reflects
more than likely Israeli concern over the availability of more
specialised Silicon, such as the Motorola 68k series, the MIPS 2/3/4000
series or the Intel i960 series CPUs currently favoured in US designs.
The standard memory size in Popeye and AGM-142 rounds has not been
disclosed.

The missile
variant being procured by the RAAF is interfaced to the aircraft via a
standard Mil-Std-1760 interface (unlike earlier variants), which
incorporates a Mil-Std-1553B serial databus, an EIA RS-170 video
interface, 28VDC power and triple phase 115V/400 Hz AC power. Once
released, the weapon runs off a pair of sizeable internal 28VDC thermal
batteries, one for electronics and the other for hydraulics. Unlike the
Harpoon, an internal avionics heater element is not used, reflecting
the
climatic conditions common to the Middle East and Asia-Pacific.

The 1553B
bus provides the launch aircraft with the means of communicating with
the missile before release, and enables diagnostic access and
initialisation of the weapon with waypoints and target coordinates. The
proper operation of the seeker may be verified before launch via the
RS-170 video feed.

Missile
control is provided by cruciform, hydraulically powered tail surfaces.
While the typical arrangement for missile hydraulics uses a gas
pressurised reservoir and discards fluid upon use, the Raptor uses a
closed cycle system powered by an electrical hydraulic pump, in turn
powered off the hydraulic system's 28VDC rail. The weapon currently has
electrical power sufficient to keep all systems operating for
significantly longer than the missile's flight time with the existing
powerplant. This suggests that future longer burn powerplants could be
used to further extend the weapon's range by a significant margin. The
existing constant thrust solid rocket propellant engine has a burn
duration in excess of two minutes.

With the
existing powerplant, the weapon will fly at transonic or supersonic
speeds, subject to mission profile. Ranges on various profiles are
classified, but are known to be well in excess of fifty nautical miles
for high altitude launches. The missile is qualified for and has flight
control software support for both low level and high altitude launches.
The missile has an 800 lb warhead. Blast fragmentation or penetration
casing versions may be fitted at depo level.

The
weapon's datalink will transmit seeker video to the launch aircraft,
and
receive aimpoint update commands. The RAAF will be acquiring USAF
standard datalink equipment, which has some differences from the
Israeli
standard equipment. The datalink pod will be carried beneath the lower
fuselage of the F-111C AUP, in the same location as the AXQ-14 datalink
pod used for the GBU-15. The pod uses a Mil-Std-1553B interface for
commands and provides an RS-170 video feed to the cockpit. This
provides a significant level of hardware compatibility with the F-111C
AUP avionic suite, which will require primarily software changes to
accommodate the new missile. Hardware changes are minimal, and involve
replacing some connectors, adding some pylon wiring, and extending the
Mil-Std-1553B databus to the aft ECM station. Datalink frequencies,
bandwidths, modulations and signal formats are properly classified, so
as to prevent third parties from developing electronic countermeasures.
The datalink has a single antenna under the rocket exhaust nozzle, the
type has not been disclosed but it is probably a cavity backed spiral
or conical spiral, judged from the geometry of the radome and required
antenna coverage.

USAF
AGM-142 missiles have been subjected to two Product Enhancement Program
(PEP) upgrades since deployment, with a third (PEP3) under way. The
RAAF
will acquire rounds to the PEP3 standard. In line with ADF policy, the
RAAF will not disclose the number of pods to be acquired, nor the
number of rounds planned. As the missile's cost, cca USD 1M, has been
published in the US, the RAAF will not disclose the total program costs
so as not to compromise policy on weapon stocks disclosure.

A issue for
the RAAF to consider in the longer term is the AGM-142E, a 2,500 lb
derivative of the basic weapon which retains the existing weapon's
warhead and propulsion, but due a redesigned and repackaged electronics
section is both shorter and 500 lb lighter. At the time of writing the
E-model was awaiting clearance testing and was not on order by the
USAF.
Should the USAF acquire this variant, it would most likely come under
serious consideration by the RAAF.

In
operational use the RAAF will typically carry a datalink pod and a pair
of Raptor rounds on the F-111C AUP aircraft. Whilst carriage of four
3,000 lb rounds is an option, the range and manoeuvrability penalties
incurred suggest that this will not be a common sight in operational
service. Should the F-111G receive a full AUP avionic upgrade, then
they
could also be made capable of launching the Raptor.

We can
expect the Raptor to be used primarily to hit high value well defended
targets such as command posts and bunkers, key air defence sites, early
warning radar sites, strategically positioned SAM sites and critical
infrastructure items. The weapon would be of particular value during
the
opening phase of an air campaign, as it would allow the RAAF to take
down key nodes in the opponent's Command-Control-Communications network
and Integrated Air Defence System. Once these are down, the IADS will
collapse, allowing the use of cheaper munitions in most instances.

The
combination of a high speed precision missile and a fast F-111 will
defeat the SA-10 and SA-12 weapon systems, and any similar future SAM
systems. The F-111 can shoot the missile at the boundaries of the SAM's
coverage, retreat from SAM range while the Raptor closes on the target,
and then via datalink control pick off the SAM's phased array
engagement
radar and command van. The cost argument is much in favour of the
F-111/Raptor, as the targeted SAM fire control system is worth tens of
millions of dollars, for the cost of a 1 million dollar missile.
Moreover, the ability to execute sniper-like precision hits from
outside the boundaries of lesser SAM system coverage provides the RAAF
with a decisive edge in any confrontation. The low frontal radar cross
section of the Raptor, which could be further reduced with absorbent
coatings, makes its detection and engagement by an opponent extremely
difficult, moreso if supported by jamming from the launching F-111
aircraft.

An issue
will be the supply of intelligence for targeting purposes.The RAAF is
at
this time investigating the fitting of imaging synthetic aperture radar
to some F-111 airframes. Such a capability would support the new SOW,
as well as provide a potent strategic reconnaissance capability.

The
acquisition of the AGM-142 Raptor SOW opens a new era in RAAF
capabilities, and will provide a significant qualitative edge against
any potential opponent in the wider Asia Pacific region. The high
performance F-111C, re-engined and fitted with digital avionics, and
armed with the Raptor, will be the most potent strike capability in
service regionally, excluding the USAF's F-117A and B-2A. As the
missile
has inherent systems and performance growth potential, it will not be
easily defeated. The marriage of the SOW and the Pig promises to be a
successful one indeed.

Under any other circumstance a Herculanean task, this USAF
Pig is
carrying four SOWs. The RAAF is planning an IOC of mid 1999 for
deployment of the AGM-142 Raptor Stand Off Weapon (SOW). A typical
operational configuration will be a rear fuselage datalink pod and a
pair of Raptor rounds. The combination of the supersonic/transonic
Raptor and the high performance, by then re-engined, F-111C will defeat
any air defence environment currently in existence or expected to exist
in the Asia Pacific region until 2010 (LMC).